Vitamin D3 treatment fails to restore glucocorticoid-induced down-regulation of interleukin-10 receptor expression on CD4+ T cells

Glucocorticoids (GC) exert some of their anti-inflammatory actions via enhancement of interleukin-10 (IL-10) production by immune cells. Interestingly, however, we previously demonstrated that oral administration of GC to asthmatic patients resulted in down-regulation of interleukin-10 receptor (IL-10R) expression on peripheral blood leukocytes. Here we wished to investigate whether addition of vitamin D3 (vit. D3) could abrogate these down-regulating actions of GC. We performed a comparative analysis of the effects of in vitro stimulation with GC and/or vit. D3 on surface expression of IL-10R on the CD4+ T cell pool. As expected, GC stimulation led to significant reduction of IL-10R. In contrast, culture in the presence of vit. D3 did not result in any significant changes of IL-10R expression. Moreover, addition of vit. D3 to GC culture did not alter GC-induced down-regulation of IL-10R expression. Thus, we conclude that anti-inflammatory actions of vit. D3 are not dependent on modification of IL-10R expression.